Archive for the ‘Metabolism’ Category

Furthermore, detachment of cells from the amnion is not an immediate death sentence since viable amniocytes can be collected from amniotic fluid, and limited digestion of amnion tissue with bacterial collagenase disperses cells that can be maintained in culture. Thus, the state of the amnion cells, the process leading to their separation from the matrix, […]

The simplest interpretation of our in vitro studies is that increased expression of the MMP-9 proenzyme leads to the formation of active enzyme, which, in turn, degrades type IV collagen, leading to amnion cell apoptosis. Alternative interpretations include the possibility that the increased proMMP-9 sequestered endogenous tissue inhibitors of me-talloproteinases, leading to increased activities of […]

Consistent with this view, our in vitro experiments demonstrated that increasing MMP-9 expression promotes collagen breakdown and apoptosis in rat amnions in organ culture. It should be noted that cells remaining anchored to the amnion, in addition to those that had separated from their substrates, were undergoing apoptosis as evidenced by nuclear DNA fragmentation. Hence, […]

Our studies demonstrating differential sensitivity of kidney and amnion basement membranes to collagen breakdown by active MMP-9 and bacterial collagenase suggest that the rat amnion type IV collagen chain composition potentially favors collagenase degradation, as compared to the type IV collagen composition of adult renal tubular basement membranes. The relative abundance of cysteine-enriched type IV […]

These structural changes in amnion basement membrane and cell attachment are temporally correlated with the rise in MMP-2 and MMP-9 activities, suggesting that the actions of the MMPs on basement membrane type IV collagen at this time are functionally significant. Further studies are needed to determine the relative contributions of changes in type IV collagen […]

The present report documents that type IV collagen is lost from the rat amnion before the onset of labor. The relative decline in type IV collagen could be the result of diminished synthesis, accumulation of other proteins in the amnion which alters the relative abundance of type IV collagen, increased degradation, or a combination of […]

Thirty hours after infection, the medium surrounding amnions infected with AdMMP-9 contained a prominent proMMP-9 signal detected as a 92-kDa lysis band by zymog-raphy and an 83-kDa band beneath it, reflecting processed proenzyme (Fig. 4), results that are consistent with transduction of cultured cells with this vector. MMP-2 activity was present in the media from […]